But the AFP's claim that the drugs were worth more than $1 billion is under scrutiny, with analysis of ice seizures publicised as recently as last month showing police are valuing Monday's haul at nearly four times the price they have used following earlier raids.

The AFP said it came up with the figure using a new "upper range" method of calculating drug prices.

Police said the 720 litres of methylamphetamine uncovered could have been used to make 504 kilos of ice with a street value of $1.26 billion - working out at $2.5 million per kilo. However, last month the AFP valued 159 kilograms of ice at $106.5 million, or approximately $666,000 per kilo.